Laminated heat exchanger

ABSTRACT

In order to prevent a communicating pipe from becoming damaged by water (in particular drain water) collecting in the gap formed between the tube element at one end of a heat exchanger that is constituted of a flat plate and a formed plate and the communicating pipe through defective brazing and repeatedly freezing and melting, a flange (32) and a bonding margin (11) continuous to the flange (32) are notched off over almost the entire circumference at the center on the inside of an indented portion (9) in a formed plate (16) which, together with a flat plate (15), constitutes a tube element (3b). Thus, while the communicating pipe (27) comes in contact with the internal surface of a flange (29) of a pipe connection hole (28) of the flat plate (15), it does not come in contact with the formed plate (16), thereby forming a gap bounded by the flat plate (15), the formed plate (16) and the communicating pipe (27).

BACKGROUND OF THE INVENTION

The present invention relates to a laminated heat exchanger that may beemployed in an evaporator or the like constituting the refrigerationcycle in an air conditioning system for vehicles, for instance, havingan inflow port and an outflow port provided side-by-side at one side inthe direction of the lamination.

The invention completed by the applicant of the present invention, whichis disclosed in Japanese Unexamined Patent Publication No. H8-121988,achieves the prevention of freezing damage or corrosion of the tubeelements or the communicating pipe which may occur in a laminated heatexchanger constituted by laminating tube elements each having a pair oftanks at one side and a groove portion formed between the tanksalternately with fins over a plurality of levels so that a communicatingpassage extends between the tanks in the direction of the laminationwith the communicating pipe mounted at the communicating passage, whenwater is collected in the gap formed through defective brazing of thecommunicating pipe and the circumferential edges of the groove portionsconstituting the communicating passage. This invention is already inuse.

According to this invention, each of the tube elements is provided witha pair of tanks and a U-shaped heat exchanging medium passagecommunicating between the pair of tanks and is constituted by bondingface-to-face a pair of formed plates. In one of the formed plates in thepair, a flange that is bent toward the non-bonding side is formed inorder to increase the strength of the formed plate over the entirecircumference at the edge portion of the brazing margin at thecircumferential edges of the distended portion for passage formation andthe distended portion for tank formation, whereas in the other formedplate, this flange and a brazing margin continuous to the flange arenotched over the entire circumferential edge of the groove portionbetween the tanks. With this, in tube elements constituted by bondingthese formed plates, only the groove portion at one of the formed platescomes in contact with the communicating pipe. Alternatively, one siderelative to the center of the circumferential edge of the groove portionin each formed plate may be notched, and in tube elements constituted bybonding such formed plates, the communicating pipe comes in contact withalternate groove portions.

As a result, since a large opening is formed between the communicatingpipe and the groove portions of the tube elements having the width overwhich the center of the circumferential edge of the groove portion atthe formed plate is notched toward the front end of the formed plate orhaving the width over which one side relative to the center of theinside circumferential edge of groove portion of the formed platenotched toward the front end of the formed plate, drainage is improvedto prevent water from collecting, so that a problem of collected waterrepeatedly freezing and melting to damage the tube element and thecommunicating pipe is eliminated. In addition, the problem of the tubeelement and the communicating pipe becoming corroded by the collectedwater, is avoided.

Now, laminated heat exchangers employing a communicating pipe includethe type illustrated in FIGS. 12 and 13, in which a formed plate 100 anda flat plate 101 are bonded to each other at one side in the directionof the lamination, a distribution plate 102 is further bonded to theflat plate 101 to form an inflow passage 103 and an outflow passage 104and one end of a communicating pipe 106 is inserted and fitted in a hole105 formed in the flat plate 101 to allow a heat exchanging medium toflow in to a specific tank through the inflow passage 103. In this heatexchanger, in order to perform brazing of the flat plate 101 and thecommunicating pipe 106 in a reliable manner, a flange 107 is formed atthe circumferential edge of the hole 105 of the flat plate 101 extendingtoward the non-bonding side that is not bonded to the formed plate 100.

If the formed plate 100, which is bonded to the flat plate 101 in thelaminated heat exchanger, is structured identically to a formed plate inthe prior art described earlier, since a bonding margin 109 thatcontains a flange 110 of the formed plate 100 is bonded to a portion ofthe flat plate 101 which is in close proximity to the flange 107 at oneend of the groove portion 108, there are potential problems that mayoccur in the event of defective brazing, in that a triangular gap Awhich is not filled with the brazing material is formed between theformed plate 100, the flat plate 101 and the communicating pipe 106 asillustrated in FIG. 14. This results in water such as the drain watercollecting in the gap A and, through a process of repeated freezing andmelting, damaging the tube element 111 constituted of the formed plate100 and the flat plate 101 or the communicating pipe 106, and in thecollected water corroding the tube element 111 or the communicating pipe106.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide alaminated heat exchanger provided with a tube element constituted of aformed plate and a flat plate at one end of the direction of thelamination of the tube elements each constituted by bonding two formedplates and fins, in which water is not allowed to readily collectbetween the tube element constituted of the formed plate and the flatplate and the communicating pipe.

Thus, in the laminated heat exchanger according to the presentinvention, which is constituted by alternately laminating over aplurality of levels tube elements each constituted by bondingface-to-face two formed plates at their bonding margins, a pair of tanksat one side with an indented portion provided therebetween and a heatexchanging medium passage communicating between the tanks, and fins, byproviding a tube element constituted of a formed plate which is formedto have a basically similar shape as the formed plates constituting theother tube elements, and a flat plate with a pipe connection holesformed therein and by providing a communicating pipe in the indentedportions between the tanks so that with the communicating pipe connectedto a specific tank, a flow path for a heat exchanging medium is formedwith an inflow port and an outflow port provided side-by-side at oneside in the direction of the lamination, an area near one side of thecommunicating pipe is not in contact with the indented portion of theformed plate in the tube element constituted of the flat plate and theformed plate.

In addition, in order to ensure that the communicating pipe does notcome in contact with the formed plate even when it is inserted andfitted in the pipe connection hole of the flat plate, a bonding marginhaving a flange may be formed at the circumferential edge of the formedplate in the tube element constituted of the flat plate and the formedplate at the inflow outflow port side, with the flange and the bondingmargin continuous to the flange notched off at the indented portionbetween the tanks.

Alternatively, the diameter of the communicating pipe in the area nearthe end that is connected to the pipe connection hole of the flat platemay be set smaller than the diameter of the indented portion of theformed plate which is bonded to the flat plate that is to form an inflowpassage and an outflow passage.

Consequently, since, while the area near the end of the communicatingpipe at one side is inserted and fitted in the pipe connection hole ofthe flat plate, the flange and the bonding margin continuous to theflange are notched at the indented portion of the formed plate which isto be bonded to the flat plate or the diameter of the communicating pipein the area near the position at which it is inserted and fitted is setsmaller than that of the indented portion of the formed plate, thecommunicating pipe does not come in contact with the indented portion ofthe formed plate. Thus, even with the communicating pipe inserted andfitted in the pipe connection hole of the flat plate, a large opening isformed between the formed plate and the communicating pipe, improvingdrainage to ensure that water is not readily collected there.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the invention and the concomitantadvantages will be better understood and appreciated by persons skilledin the field to which the invention pertains in view of the followingdescription given in conjunction with the accompanying drawings whichillustrate a preferred embodiment. In the drawings:

FIG. 1A is a front view illustrating the structure of the laminated heatexchanger according to the present invention and FIG. 1B is a bottomview illustrating the structure of the laminated heat exchangeraccording to the present invention;

FIG. 2 is a front view illustrating the structure of a formed plate thatconstitutes the principal tube elements in the laminated heat exchangerabove;

FIG. 3A is a front view illustrating the structure of a flat platebonded to a distribution plate which is to form an intake port, and FIG.3B is a cross section of the flat plate;

FIG. 4 is an enlargement illustrating, in essence, the structure of theformed plate bonded to the flat plate;

FIG. 5 is an enlargement illustrating, in essence, a communicating pipemounted at an indented portion achieved by bonding face-to-face twoformed plates;

FIG. 6 is a cross section illustrating the communicating pipe mounted atthe indented portion achieved by bonding face-to-face the two formedplates;

FIG. 7 is an enlargement illustrating, in essence, the communicatingpipe brazed at the indented portion of the tube element constituted bybonding the formed plates above;

FIG. 8 is an enlargement illustrating, in essence, the communicatingpipe inserted and fitted in a hole of the flat plate for forming inflowpassage and an outflow passage bonded to an formed plate;

FIG. 9 is a cross section illustrating the communicating pipe insertedand fitted in the hole of the flat plate above bonded to the formedplate;

FIG. 10 is a cross section illustrating the communicating pipe brazed atthe indented portion of the tube element constituted by bonding the flatplate above and the formed plate above;

FIG. 11 is a cross section illustrating the communicating pipe, whosediameter at the area near the position of the insertion is reduced,inserted and fitted at the tube element constituted by bonding theformed plate shown in FIG. 2 and the flat plate shown in FIG. 3;

FIG. 12 is a cross section illustrating a prior art communicating pipe,having a consistent diameter, inserted and fitted at a tube elementconstituted by bonding the formed plate shown in FIG. 2 and the flatplate shown in FIG. 3;

FIG. 13 is an enlargement illustrating, in essence, the state shown inFIG. 12 viewed from the direction indicated by the arrow in FIG. 12; and

FIG. 14 is an enlargement illustrating, in essence, the state in which agap is formed, bounded by the formed plate, the flat plate and thecommunicating pipe through defective brazing in the example of the priorart above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following is an explanation of the preferred embodiment of thepresent invention in reference to the drawings.

FIGS. 1A and 1B show an evaporator 1 employed in an air conditioningsystem for vehicles, for instance, as the laminated heat exchangeraccording to the present invention, which may adopt a four-pass system,for instance, with fins 2 and tube elements 3 laminated alternately overa plurality of levels to form a core main body and an inflow port 4 andan outflow port 5 for heat exchanging medium provided at one end in thedirection of the lamination of the tube elements 3. The tube elements 3are each constituted by bonding face-to-face two formed plates 6, one ofwhich is shown in FIG. 2, except for tube elements 3a and 3b at the twoend portions of the core main body in the direction of the lamination, atube element 3c having an expanded tank which is to be detailed laterand a tube element 3d located at approximately the center.

The formed plates 6 are each formed by press machining an aluminum alloywhose main constituent is aluminum with both surfaces thereof clad witha brazing material, having two bowl-shaped distended portions for tankformation 7 and 7 formed at one end, a distended portion for passageformation 8 formed continuous to them, an indented portion for pipemounting 9 for mounting a communicating pipe 27, which is to be detailedlater, formed between the distended portions for tank formation 7 and 7and a partitioning wall 10 formed extending from the area between thetwo distended portions for tank formation 7 and 7 to the vicinity of theother end of the formed plate 6. In addition, a plurality of beads (notshown) are formed arrayed with a specific regularity at the distendedportion for passage formation 8. It is to be noted that an arc-shapedindentation 9a may be formed at the indented portion for pipe mounting 9toward the partitioning wall 10, as illustrated in FIGS. 2 and 4.

The distended portions for tank formation 7 and 7 distend to a largerdegree than the distended portion for passage formation 8 and thepartitioning wall 10 is formed on the same plane as a bonding margin 11at the peripheral edges of the formed plate 6. Thus, when two formedplates 6 are bonded to each other at their peripheral edges, theirpartitioning walls 10 become bonded to each other so that a pair oftanks 12 and 12 are formed by the distended portions for tank formation7 and 7 that face opposite each other and a U-shaped heat exchangingmedium passage 13 connecting between the tanks 12 and 12 is formed bythe distended portions for passage formation 8 which face opposite eachother.

The tube element 3a at one side in the direction of the lamination isconstituted by bonding a flat plate 14 with no indentations orprojections to a formed plate 6 illustrated in FIG. 2, whereas the tubeelement 3b at the other side is constituted by bonding a flat plate 15having a pipe connection hole 28 with a flange 29 (which is to bedetailed later) formed at its circumferential edge and a communicatinghole 30 as illustrated in FIG. 3 to a formed plate 16 illustrated inFIG. 4. Thus, tanks 12a and 12a whose capacity is approximately half ofthe capacity of the tanks 12 and 12 of the tube elements 3 are formed.

In addition, the tube element 3c is constituted by bonding face-to-faceformed plates 17 and 17 in each of which one of the distended portionsfor tank formation is expanded so that it approaches the other distendedportion for tank formation, and consequently, in the tube element 3c atank 12 whose size is the same as that of the tanks 12 formed in theother tube elements 3, and a tank 12b which is expanded to fill theindented portion for pipe mounting 9, are formed.

Furthermore, in the evaporator 1, as illustrated in FIGS. 1A and 1B,adjacent tube elements are abutted at their tanks 12 and 12a, with twotank groups, i.e., a first tank group 18 and a second tank group 19,extending in the direction of the lamination (the directionperpendicular to the direction of the airflow) constituted by a seriesof abutted tanks 12. In the first tank group 18 that includes theexpanded tank 12b, the individual tanks 12 are in communication witheach other through communicating holes 20 (shown in FIG. 2) formed atthe distended portions for tank formation 7 except at the tube element3d, which is located at approximately the center in the direction of thelamination.

More specifically, the tube element 3d is constituted by bondingface-to-face the formed plate 6 shown in FIG. 2 and a formed plate 21which is formed similar to the formed plate 6 but without acommunicating hole formed at one of its distended portions for tankformation 7 to form a blind tank 12c. This tube element 3d divides thefirst tank group 18 into a first tank block α that includes the expandedtank 12b and a second tank block β that communicates with the outflowport 5. In addition, in the second tank group 19, all the tanks are incommunication with each other through communicating holes 20 withoutpartitioning to constitute a third tank block γ.

At one end in the direction of the lamination, a distribution plate 22is bonded to the flat plate 15 as illustrated in FIGS. 1A and 1B. Inthis distribution plate 22, two bulging portions, i.e., a first bulgingportion 23 and a second bulging portion 24, are formed distendingside-by-side through press machining, with the inflow port 4 provided atone end of the first bulging portion 23 and the outflow port 5 providedat the end of the second bulging portion 24 at the same side. Inaddition, a brazing material is clad only on the internal surface of thedistribution plate 22 in the direction of the lamination (the surface tobe bonded to the flat plate 15). The flat plate 15, too, is clad with abrazing material only on its internal surface in the direction of thelamination. Thus, by bonding the distribution plate 22 to the flat plate15, using the brazing material at the distribution plate 22, an inflowpassage 25 communicating with the inflow port 4 and an outflow passage26 communicating with the outflow port 5 are formed between thedistribution plate 22 and the flat plate 15. The inflow passage 25communicates with the communicating pipe 27 by connecting thecommunicating pipe 27, whose one end is connected to the expanded tank12b at the pipe connection hole 28 of the flat plate 15 with the flange29 formed at its circumferential edge at the other end using the brazingmaterial at the communicating pipe 27 and the brazing material at theflat plate 15, whereas the outflow passage 26 communicates with thesecond tank block β via the communicating hole 30 of the flat plate 15.In addition, a coupling 31 for securing an expansion valve is bonded tothe inflow port 4 and the outflow port 5.

Thus, the heat exchanging medium that has flowed in through the inflowport 4 enters the expanded tank 12b through the inflow passage 25 andthe communicating pipe 27 to become dispersed over the entire first tankblock α, and then flows via the heat exchanging medium passages of thetube elements corresponding to the first tank block α along thepartitioning walls 10 (first pass). Then, it travels downward aftermaking a U-turn above the partitioning walls 10 (second pass) andreaches the tank group at the opposite side (the third tank block γ).After this, it moves horizontally to the remaining tube elementsconstituting the third tank block γ to flow through the heat exchangingmedium passages 13 of the remaining tube elements along theirpartitioning walls 10 (the third pass). Next, it makes a U-turn abovethe partitioning walls 10 before traveling downward (the fourth pass),is led to the tanks constituting the second tank block β, and then ittravels through the outflow passage 26 to flow out through the outflowport 5. Thus, the heat of the heat exchanging medium is conducted to thefins 2 during the process in which it flows through the heat exchangingmedium passages 13 corresponding to the first through fourth passes sothat heat exchange is performed with the air passing between the fins 2and 2.

It is to be noted that while the formed plates 6 (also the formed plates17 and 21) are each provided with a flange 32 which is constituted bybending edge portions of the bonding margin 11 at the circumferentialedge of the distended portion for passage formation 8 and the bondingmargin 11 of the distended portions for tank formation 7 toward thenon-bonding side, as illustrated in FIG. 2, in order to increase thestrength of the formed plate 6, a notched portion 33 is formed at thecircumferential edge of the indented portion for pipe mounting 9 betweenthe distended portions for tank formation 7 and 7 by notching in an arcshape the flange 32 and the bonding margin 11 continuous to the flange32 except at the area where the arc-shaped indentation 9a is formed atone side relative to the center on the inside of the indented portionfor pipe mounting 9. In other words, at the indented portion for pipemounting 9, the diameter at one side with the center of its inside, isexpanded.

Thus, as illustrated in FIGS. 5 and 6, since the flange and the bondingmargin are eliminated at the indented portion for pipe mounting 9 at thedistended portions for tank formation 7 in the formed plate 6 by thenotched portion 33, when two formed plates 6 and 6 are bonded to eachother, a size difference of approximately 0.6 mm over which the flange32 and the like of the other formed plate 6 is visible at each formedplate 6 is alternately formed at the indented portions 9. Thus, when thecommunicating pipe 27 is fitted at the indented portions for pipemounting 9, the tube element 3 comes in contact with the communicatingpipe 27 at the flange 32 at one of the indented portions for pipemounting 9 in the formed plate 6 but does not come in contact with thecommunicating pipe 27 at the other indented portion 9 due to the sizedifference.

Consequently, when the assembled body of the evaporator 1 is brazed in afurnace after mounting the communicating pipe 27 at the indented portionfor pipe mounting 9, a large opening is formed in alternate directionsin the space formed by the formed plates 6 and 6 and the communicatingpipe 27 to the tube element 3, as illustrated in FIG. 7, since portionsof the flange and the bonding margin are removed. This improves drainageand even if water enters the gap, it is less likely to collect there.

In contrast, the formed plate 16 constituting the tube element 3blocated at one end of the evaporator illustrated in FIG. 4 has astructure that is partially different at its notched portion 33 from theformed plate 6. Namely, notched portions 33 and 33 are formed bynotching in an almost arc shape the flange 32 and the bonding margin 11continuous to the flange 32 except at the area where the arc shapedindentation 9a is formed at the two sides relative to the center on theinside of the indented portion for pipe mounting 9.

Thus, as illustrated in FIGS. 8 and 9, since the flange and the bondingmargin are removed at the indented portion for pipe mounting 9 betweenthe distended portions for tank formation 7 by the notched portions 33in the formed plate 16, when the communicating pipe 27 is inserted andfitted in the pipe connection hole 28 of the tube element 3b, thecommunicating pipe 27 comes in contact with the internal surface of theflange 29 at the flat plate 15 but does not come in contact with thetube element 3b toward the formed plate 16 side.

As a result, as illustrated in FIG. 10, a large opening is providedoriented toward the inside in the direction of the lamination of theevaporator in the space formed by the flange 29 of the flat plate 15,the formed plate 16 and the communicating pipe 27 since portions of theflange and the connecting margin are not present at the formed plate 16,thereby improving the drainage, which prevents water that has enteredthe gap from becoming collected in the gap readily.

The communicating pipe 27 may be prevented from coming in contact withthe indented portion for pipe mounting 9 of the formed plate bonded tothe flat plate 15 by other means than forming the notched portions 33 atthe formed plate at the two sides relative to the center on the insideas described above. Namely, as illustrated in FIG. 11, while the formedplate 6 illustrated in FIG. 2 is bonded to the flat plate 15, thediameter of the communicating pipe 27 in an area near one end may bereduced with the diameter of the pipe connection hole 28 at the flatplate 15 also reduced in correspondence to the reduced diameter of thecommunicating pipe, instead.

In this case, even with the flange 32 remaining at one side of theformed plate bonded to the flat plate 15 relative to the center on theinside of the indented portion 9, a sealed space between the flange 32and the communicating pipe 27 is eliminated to a degree corresponding tothe reduction in the diameter of the communicating pipe 27 after theevaporator 1 is brazed, thereby improving the drainage and preventingwater that has entered the space from collecting readily. In addition,since all the notched portions 33 of the formed plates can be formed atone side relative to the center on the inside, the manufacturing processfor manufacturing the formed plates is simplified.

As has been explained, according to the present invention, since theportion of the communicating pipe near one end is not in contact withthe indented portion of the formed plate which is bonded to the flatplate toward the outflow port, a large opening is formed between theformed plate and the communicating pipe to make it less likely thatwater will collect in the space formed by the flat plate forconstituting the inflow passage and the outflow passage, the formedplate and the communicating pipe. Thus, the communicating pipe and thetube elements are prevented from being damaged by the water repeatingthe process of freezing and melting. In addition, since the drainage isimproved and water does not collect in the space readily, corrosion ofthe communicating pipe and the tube elements is prevented.

What is claimed is:
 1. A laminated heat exchanger comprising:first tubeelements, each of which is constituted by bonding face-to-face a pair offormed plates and has a pair of tanks provided at one end in alengthwise direction thereof, a heat exchanging medium passagecommunicating between said pair of tanks and an indented portion formedbetween said pair of tanks, each of said tanks having a pair ofcommunication holes in a lamination direction of said laminated heatexchanger; second tube elements provided at both sides in saidlamination direction of said laminated heat exchanger, each of which isconstituted by bonding face-to-face a formed plate and a flat plate andhas a pair of tanks provided at one end in a lengthwise directionthereof, a heat exchanging medium passage communicating between saidpair of tanks and an indented portion formed between said pair of tanks,each of said tanks having a communication hole at one end in saidlamination direction and opposite said flat plate, said flat plate ofone of said second tube elements being provided with a pipe connectionhole at an approximate center of one end thereof in said lengthwisedirection, said pipe connection hole being open at said indentedportion; a third tube element constituted by bonding face-to-face a pairof formed plates and having a pair of tanks provided at one end in alengthwise direction thereof and a heat exchanging medium passagecommunicating between said pair of tanks, said tanks havingcommunication holes at both sides in said lamination direction, one ofsaid pair of tanks being an expanded tank extending out to an area nearthe other of said pair of tanks; a fourth tube element constituted bybonding face-to-face a pair of formed plates and having a pair of tanksprovided at one end in a lengthwise direction thereof and a heatexchanging medium passage communicating between said pair of tanks, oneof said pair of tanks having communication holes at both sides in saidlamination direction, the other of said pair of tanks having acommunication hole at one side in said lamination direction and nocommunication hole in the other side in said lamination direction so asto constitute a blind tank; fins alternately laminated with said firsttube elements, said second tube elements, said third tube element andsaid fourth tube element; a distribution plate provided on an outside ofsaid one of said second tube elements, said distribution plate beingprovided with an inflow passage communicated with an inflow port forheat exchanging medium and an outflow passage communicated with anoutflow port for heat exchanging medium; a communicating pipecommunicating between said expanded tank and said inflow passage, saidcommunicating pipe being located in said indented portions andpositioned between said third tube element with said expanded tank andone of said second tube elements, one end of said communicating pipebeing inserted into said pipe connection hole; wherein said pairs oftanks of said first tube elements, said second tube elements, said thirdtube element and said fourth tube element together form a first tankgroup and a second tank group, said first tank group being divided intofirst and second tank blocks by said blind tank, said second tank groupbeing in communication throughout to constitute a third tank block, saidexpanded tank of said third tube element being located in one of saidfirst and second tank blocks and remote from said flat plate of said oneof said second tube elements; and wherein said one end of saidcommunicating pipe inserted into said pipe connection hole is providedwith a small diameter portion whose diameter is smaller than a width ofsaid indented portion of said formed plate of said one of said secondtube elements, said communicating pipe being detached, at said smalldiameter portion thereof, from said indented portion of said one of saidsecond tube elements.
 2. A laminated heat exchanger according to claim1, whereinsaid formed plate of said one of said second tube elements isprovided with a bonding margin at a circumferential edge thereof and aflange bent from said bonding margin toward a non-bonding side, and anotched portion is formed by notching a contact portion of said flangein contact with said communicating pipe at said indented portion, saidcommunicating pipe being detached from said indented portion in saidnotched portion.
 3. A laminated heat exchanger according to claim 1,whereinan arc-shaped portion notched in an arc shape is formed at acentral area of said indented portion of each of said first tubeelements, said one of said second tube elements and said fourth tubeelement.
 4. A laminated heat exchanger according to claim 1, whereineachof said formed plates of said first tube elements, said second tubeelements and said fourth tube element is provided with a notched portionformed by notching over a specific range one side of said flangeprovided at both sides of said indented portion in contact with saidcommunicating pipe.
 5. A laminated heat exchanger according to claim 3,whereineach of said formed plates of said first tube elements, saidsecond tube elements and said fourth tube element is provided with anotched portion formed by notching over a specific range one side ofsaid flange provided at both sides of said indented portion in contactwith said communicating pipe.
 6. A laminated heat exchangercomprising:first tube elements, each of which is constituted by bondingface-to-face a pair of formed plates and has a pair of tanks provided atone end in a lengthwise direction thereof, a heat exchanging mediumpassage communicating between said pair of tanks and an indented portionformed between said pair of tanks, each of said tanks having a pair ofcommunication holes in a lamination direction of said laminated heatexchanger; second tube elements provided at both sides in saidlamination direction of said laminated heat exchanger, each of which isconstituted by bonding face-to-face a formed plate and a flat plate andhas a pair of tanks provided at one end in a lengthwise directionthereof, a heat exchanging medium passage communicating between saidpair of tanks and an indented portion formed between said pair of tanks,each of said tanks having a communication hole at one end in saidlamination direction and opposite said flat plate, said flat plate ofone of said second tube elements being provided with a pipe connectionhole at an approximate center of one end thereof in said lengthwisedirection, said pipe connection hole being open at said indentedportion, wherein said flat plate of said one of said second tubeelements has a cylindrical flange extending out from a circumferentialedge of said pipe connection hole in an insertion direction of saidcommunicating pipe; a third tube element constituted by bondingface-to-face a pair of formed plates and having a pair of tanks providedat one end in a lengthwise direction thereof and a heat exchangingmedium passage communicating between said pair of tanks, said tankshaving communication holes at both sides in said lamination direction,one of said pair of tanks being an expanded tank extending out to anarea near the other of said pair of tanks; a fourth tube elementconstituted by bonding face-to-face a pair of formed plates and having apair of tanks provided at one end in a lengthwise direction thereof anda heat exchanging medium passage communicating between said pair oftanks, one of said pair of tanks having communication holes at bothsides in said lamination direction, the other of said pair of tankshaving a communication hole at one side in said lamination direction andno communication hole in the other side in said lamination direction soas to constitute a blind tank; fins alternately laminated with saidfirst tube elements, said second tube elements, said third tube elementand said fourth tube element; a distribution plate provided on anoutside of said one of said second tube elements, said distributionplate being provided with an inflow passage communicated with an inflowport for heat exchanging medium and an outflow passage communicated withan outflow port for heat exchanging medium; a communicating pipecommunicating between said expanded tank and said inflow passage, saidcommunicating pipe being located in said indented portions andpositioned between said third tube element with said expanded tank andone of said second tube elements, one end of said communicating pipebeing inserted into said pipe connection hole; wherein said pairs oftanks of said first tube elements, said second tube elements, said thirdtube element and said fourth tube element together form a first tankgroup and a second tank group, said first tank group being divided intofirst and second tank blocks by said blind tank, said second tank groupbeing in communication throughout to constitute a third tank block, saidexpanded tank of said third tube element being located in one of saidfirst and second tank blocks and remote from said flat plate of said oneof said second tube elements; and wherein said indented portion of saidformed plate of said one of said second tube elements is detached fromsaid communicating pipe.
 7. A laminated heat exchanger comprising:firsttube elements, each of which is constituted by bonding face-to-face apair of formed plates and has a pair of tanks provided at one end in alengthwise direction thereof, a heat exchanging medium passagecommunicating between said pair of tanks and an indented portion formedbetween said pair of tanks, each of said tanks having a pair ofcommunication holes in a lamination direction of said laminated heatexchanger; second tube elements provided at both sides in saidlamination direction of said laminated heat exchanger, each of which isconstituted by bonding face-to-face a formed plate and a flat plate andhas a pair of tanks provided at one end in a lengthwise directionthereof, a heat exchanging medium passage communicating between saidpair of tanks and an indented portion formed between said pair of tanks,each of said tanks having a communication hole at one end in saidlamination direction and opposite said flat plate, said flat plate ofone of said second tube elements being provided with a pipe connectionhole at an approximate center of one end thereof in said lengthwisedirection, said pipe connection hole being open at said indentedportion, wherein said flat plate of said one of said second tubeelements has a cylindrical flange extending out from a circumferentialedge of said pipe connection hole in an insertion direction of saidcommunicating pipe; a third tube element constituted by bondingface-to-face a pair of formed plates and having a pair of tanks providedat one end in a lengthwise direction thereof and a heat exchangingmedium passage communicating between said pair of tanks, said tankshaving communication holes at both sides in said lamination direction,one of said pair of tanks being an expanded tank extending out to anarea near the other of said pair of tanks; a fourth tube elementconstituted by bonding face-to-face a pair of formed plates and having apair of tanks provided at one end in a lengthwise direction thereof anda heat exchanging medium passage communicating between said pair oftanks, one of said pair of tanks having communication holes at bothsides in said lamination direction, the other of said pair of tankshaving a communication hole at one side in said lamination direction andno communication hole in the other side in said lamination direction soas to constitute a blind tank; fins alternately laminated with saidfirst tube elements, said second tube elements, said third tube elementand said fourth tube element; a distribution plate provided on anoutside of said one of said second tube elements, said distributionplate being provided with an inflow passage communicated with an inflowport for heat exchanging medium and an outflow passage communicated withan outflow port for heat exchanging medium; a communicating pipecommunicating between said expanded tank and said inflow passage, saidcommunicating pipe being located in said indented portions andpositioned between said third tube element with said expanded tank andone of said second tube elements, one end of said communicating pipebeing inserted into said pipe connection hole; wherein said pairs oftanks of said first tube elements, said second tube elements, said thirdtube element and said fourth tube element together form a first tankgroup and a second tank group, said first tank group being divided intofirst and second tank blocks by said blind tank, said second tank groupbeing in communication throughout to constitute a third tank block, saidexpanded tank of said third tube element being located in one of saidfirst and second tank blocks and remote from said flat plate of said oneof said second tube elements; and wherein said formed plate of said oneof said second tube elements is provided with a bonding margin at acircumferential edge thereof and a flange bent from said bonding margintoward a non-bonding side, and a notched portion is formed by notching acontact portion of said flange in contact with said communicating pipeat said indented portion, said communicating pipe being detached fromsaid indented portion in said notched portion.
 8. A laminated heatexchanger according to claim 1, whereinsaid flat plate of said one ofsaid second tube elements has a cylindrical flange extending out from acircumferential edge of said pipe connection hole in an insertiondirection of said communicating pipe.
 9. A laminated heat exchangeraccording to claim 2, whereinsaid flat plate of said one of said secondtube elements has a cylindrical flange extending out from acircumferential edge of said pipe connection hole in an insertiondirection of said communicating pipe.
 10. A laminated heat exchangeraccording to claim 3, whereinsaid flat plate of said one of said secondtube elements has a cylindrical flange extending out from acircumferential edge of said pipe connection hole in an insertiondirection of said communicating pipe.
 11. A laminated heat exchangeraccording to claim 4, whereinsaid flat plate of said one of said secondtube elements has a cylindrical flange extending out from acircumferential edge of said pipe connection hole in an insertiondirection of said communicating pipe.
 12. A laminated heat exchangeraccording to claim 5, whereinsaid flat plate of said one of said secondtube elements has a cylindrical flange extending out from acircumferential edge of said pipe connection hole in an insertiondirection of said communicating pipe.